It has been assumed widely that acidification in the male reproductive tract may play an important role in maturation of sperm. However, the process of acidification and its physiologic determinants has not been investigated in detail. The primary objective of this proposed series of studies is to more clearly define the mechanism(s) of luminal fluid acidification by the direct determination of pH and (for the first time) PCO2 and bicarbonate concentration in vivo in seminiferous tubules, efferent ducts and the epididymal duct of the rat utilizing micropuncture, microelectrode and microcalorimetric techniques. In this series of studies, three specific areas will be investigated: 1) Direct evaluation of the determinants of luminal fluid acidification in the testis and epididymis and evaluation of the functional role of carbonic anhydrase in this process. 2) Evaluation of the functional role of circulating androgens in mediating luminal fluid acidification in the testis and epididymis. 3) Direct determination of the effect of bilateral vesectomy on luminal fluid acidification and ion composition in the testis and epididymis. The proposed studies will utilize highly reliable glass microelectrodes, microcalorimetric and microanalytical techniques in concert to evaluate the extent and determinants of luminal fluid acidification directly by application of testicular and epididymal micropuncture. As such these studies are designed to determine the extent and significance of luminal fluid acidification in the testis and epididymis by the use of new methodological techniques. The factors responsible for the generation and maintenance of the observed pH gradient between luminal fluid and systemic arterial blood in the testis and epididymis will be evaluated. By employing a "family" of carbonic anhydrase inhibitors the physiological role of the enzyme in luminal fluid acidification can be more clearly defined. Subcutaneous injection and oral administration of the "pure" antiandrogens cyproterone and flutamide will allow a precise definition of the role of androgen in the process of luminal acidification in the testis and epididymis. Finally, the short and long term effects of bilateral vasectomy on acid-base and ionic composition of luminal fluid in the testis and epididymis will be evaluated by micropuncture techniques.